Chemical Modification of Selected Root and Tuber Starches as Thickening and Stabilizing Agents in Double-Strength Fruit Juice

Abstract

The food application of native and chemically modified starches from white guinea yam (Discorea rotundata) and sweet potato (Ipoema batatas) tubers as substitute for cereal starches was studied.  Yam tuber and potato root were processed to extract their native starches. The native starch were chemically modified by acid hydrolysis using dilute hydrochloric acid, acetylated with acetic anhydride and oxidized with sodium hypochlorite respectively. The starch samples   were analyzed for rheological and functional properties, using commercial corn starch as a control. The starch samples were further incorporated into single strength orange juice as thickening and stabilizing agent. Triplicate values of data obtained were analyzed using SPSS Version 22 and means were compared for significant difference at 95% confidence level using Turkey’s LSD Test. Results showed that modified yam and potato starches recorded high values in all the rheological and functional parameters considered. Sensory evaluation scores of the orange fruit juice show that some yam and potato starches were superior to the commercial corn starch in all the attributes considered. It follows that imported cereal starch can be conveniently substituted with root and tuber starches to meet the industrial demand of starch in developing economies.